Rigid high power and high speed lasing grid structures

ABSTRACT

Disclosed herein are various embodiments for stronger and more powerful high speed laser arrays. For example, an apparatus is disclosed that comprises an active mesa structure in combination with an electrical waveguide, wherein the active mesa structure comprises a plurality of laser regions within the active mesa structure itself, each laser region of the active mesa structure being electrically isolated within the active mesa structure itself relative to the other laser regions of the active mesa structure.

CROSS REFERENCE AND PRIORITY CLAIM TO RELATED PATENT APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 17/156,193, filed Jan. 22, 2021, now U.S. Patent No.11,557,879, which is a continuation of U.S. patent application Ser. No.16/699,897, filed Dec. 2, 2019, now U.S. Pat. No. 10,903,622, which is acontinuation of U.S. patent application Ser. No. 16/215,069, filed Dec.10, 2018, now U.S. Pat. No. 10,498,106, which is a continuation of U.S.patent application Ser. No. 15/223,712, filed Jul. 29, 2016, now U.S.Pat. No. 10,153,615, which claims priority to (1) U.S. provisionalpatent application Ser. No. 62/199,117, filed Jul. 30, 2015, and (2)U.S. provisional patent application Ser. No. 62/272,242, filed Dec. 29,2015, the entire disclosures of each of which are incorporated herein byreference.

INTRODUCTION

Laser arrays are becoming important in the field of communications,light detection and ranging (LiDaR), and materials processing because oftheir higher operational optical power and high frequency operation ascompared to single lasers, fiber lasers, diode pumped solid state (DPSS)lasers, and light emitting diodes (LEDs).

Laser arrays are commonly used in printing and communications, but inconfigurations which have a single separate connection to each laserdevice in the array for parallel communication where each laser couldhave a separate signal because it had a separate contact from the otherdevices in the array.

When array elements were tied together and driven with a single signal,the structures had too much capacitance or inductance. This highcapacitance/inductance characteristic slowed the frequency response forthe laser array down, thereby making such laser arrays slower as theyadded more elements. This is evidenced in the referenced works byYoshikawa et al., “High Power VCSEL Devices for Free Space OpticalCommunications”, Proc. of Electronic Components and TechnologyConference, 2005, pp. 1353-58 Vol. 2, and U.S. Pat. No. 5,978,408.

High speed laser arrays based on multi-mesa structures are described inthe inventor's previous work, US Pat App. Pub. 2011/0176567. US Pat App.Pub. 2011/0176567 describes a multi-mesa array of semiconductor lasersand their connections to a high speed electrical waveguide for highfrequency operation. However, the multi-mesa structures described in USPat App. Pub. 2011/0176567 suffers from a number of shortcomings.

One problem with mesa structures as described in US Pat App. Pub.2011/0176567 is they are typically brittle. This is a problem if thereis any mechanical procedure to bond to or touch the laser after the mesais formed. The mesas structures can be as small as 5 to 10 microns indiameter and consist of an extremely fragile material such as GaAs orAlGas, or other similar crystalline materials. These mesas must bebonded after processing and pressure is applied under heat so that thesubmount and the tops of the laser mesas are bonded electrically withsolder. When bonding an array of back emitting devices a typical failuremechanism at bonding is a cracked mesa which renders the laser uselessand can cause a rejection of the entire device. If there are 30 laserson the chip and after bonding 2 are broken, those 2 devices will notlight up. The testing still must be done causing an expensive process toremove failures.

Another problem is that the multi-mesa structure yields relatively lowlasing power as a function of chip real estate because of spacingrequirements for the multiple mesas that are present on the laser chip.

Another problem with the multiple mesa arrays produced by mesa isolationis that the lasers are separated by a distance which limits the overallsize of the array due to frequency response-dependent design parametersthat prefer shorter distance for a signal to travel across a contactpad. Later, arrays were used with elements which add in power such asthe multi Vertical Cavity Surface Emitting Laser (VCSEL) arrays whichwere used for infrared (IR) illumination. However these IR sources didnot support high frequency operation, so their pulse width was limitedto illumination instead of LIDAR, which needs fast pulse widths.

In an effort to satisfy needs in the art for stronger and more powerfulhigh speed laser arrays, the inventor discloses a number of inventiveembodiments herein. For example, embodiments of the invention describedbelow incorporate a high frequency electrical waveguide to connectlasers of the array together while reducing capacitance by forming thesignal pad on the substrate which employs the electrical waveguide.Embodiments of the invention also comprise the use of multi-conductivecurrent confinement techniques in a single structure to produce multipleareas that are conducting compared to non-conducting part of thestructures. The conducting parts form lasing areas or grids of lasingforming lasers without etching around the entire structure of the lasingpoint. Unlike the design described in the above-referenced U.S. Pat. No.5,978,408, embodiments of the invention disclosed herein are designedand processed so that the laser array is integrated with a high speedelectrical waveguide to enable high frequency operation. Embodiments ofthe present invention support new and unique opportunities in the designof a high power high speed light sources by exhibiting both highfrequency operation and a rigid structure, thus enhancing performanceand reliability over other designs known in the art.

In an example embodiment disclosed herein, a unique structure processedfrom a Vertical Cavity Surface Emitting Laser (VCSEL) epitaxial materialforms a grid of laser points from a single rigid structure which isconducive to high speed operation by reducing capacitance, increasingstructural integrity, and decreasing the fill factor as compared to thetypical mesa structures formed in VCSEL arrays such as those mentionedin US Pat App. Pub. 2011/0176567. It should be understood that the VCSELembodiment is only an example, and such a design can work with otherlaser types, such as Resonant Cavity Light Emitting Diodes (RCLEDs),LEDs, or Vertical Extended (or External) Cavity Surface Emitting Lasers(VECSELs).

The single contiguous structure described herein forms areas ofelectrical isolation of apertures using implanting of ions or areas ofnonconductive oxidation through microstructures or holes while keepingthe structural integrity of the material that is typically etched away.The formation of the new structure also allows a high speed signal to bedistributed between the different isolated laser conduction points orgrid. All of the P-contact areas of the laser grid can be connected inparallel to the signal portion of a ground-signal-ground (GSG)integrated electrical waveguide. The signal or current being switched onand off in the waveguide is distributed between all of the conductivepaths which form lasers. It should be understood that other types ofelectrical waveguides could be used such as a micro-strip waveguide.

The single contiguous structure has other benefits such as a larger basefor heat distribution within a larger plating structure. The lasing gridis closer together than the array structures to each other. The fartherthe lasers are apart the slower the frequency response or the speedwhich limits the ultimate bandwidth of the device due to the distancethe signal must travel to every single point in an array.

Accordingly, examples of advantages that arise from embodiments of theinvention include:

1. Rigid structure has a higher reliability in the chip bonding process

2. Rigid structure has a higher fill factor possibility

3. Rigid structure has higher reliability metal contacts

4. Rigid structure is simpler to process

5. Rigid structure has shorter distance between contacts enabling higherfrequency high power beams

6. Rigid structure is a better surface topology for a single lens orlens array to be attached

7. Rigid mesa structure produces another area for leads and contactswhich offer separation from potentials lowering capacitance.

8. Rigid structures allow higher integration with sub mounts because ofthe 3D nature of the contacts.

Furthermore, with an example embodiment, a laser grid is formed by morethan one lasing area enabled by confining the current to isolatedregions in the structure where conductivity exists as compared to thenonconductive ion implanted areas. The conductive and nonconductiveareas form a grid of light which has a single metal contact on thesingle solid structure for the active Positive contact and a single NContact on the surrounding ground structure which is shorted to the Ncontact area at the bottom of the trench isolating the two areas. By wayof example, FIG. 7E shows how an opening in the frame would helpincrease the speed.

These P and N contacts are then bonded to a high speed electricalcontact The 2 substrate and laser chips are aligned by a bonder thenheat and pressure are applied to bond the solder that has been depositedon one chip or the other. The high speed is enabled because the p pad isseparated from the n wafer ground by plating and solder heights butmostly by removing it off the laser substrate and placing it on anelectrical waveguide substrate. The physical separations dramaticallyreduces capacitance increasing the frequency response which is limitedby the capacitance of the circuit. This enables the lasing grid toachieve high frequency operation.

A single lens formed on the back of the substrate or a single Lensattached or bonded to the back of the grid structure could direct eachlasing point from a convergence point or to a convergence point. This isideal in collimating the beam output as if it were from a single source.

These and other features and advantages of the present invention will bedescribed hereinafter to those having ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show various views of an example top-emitting implantembodiment.

FIG. 6 shows a view of an example bottom-emitting implant embodiment.

FIGS. 7A-E show views of an example top-emitting oxidation embodiment.

FIGS. 8-14C show various views of an example bottom-emitting oxidationembodiment.

FIG. 15 shows a view of an example microstrip embodiment.

FIG. 16 shows a view of an example phase coherent embodiment.

FIG. 17 shows a view of an example embodiment that employs diffractiveoptical elements.

FIG. 18 shows a view of an example embodiment that employs patterndiffractive grating.

FIG. 19 shows a view of an example microlens embodiment.

FIG. 20 shows a view of an example tenth embodiment.

FIG. 21 shows a view of an example eleventh embodiment.

FIG. 22 shows a view of an example twelfth embodiment.

FIG. 23 shows an example of an additional pattern for a lasing grid withrespect to various embodiments.

FIG. 24 comparatively shows current flow as between an exampleembodiment designed as described herein and that taught by US Pat App.Pub. 2011/0176567.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS Embodiment 1—Top-EmittingImplant

FIG. 1 shows an example of a first embodiment of the invention. In thisexample, a single solid structure is isolated from a surrounding groundwith an etch, and where the single solid structure has within it ionimplants. The ion implants create areas of the semiconductor materialthat are non-conductive, and these areas of non-conductivity forcecurrent flow through the lasing areas 2. Thus, the ion implants form alaser grid of multiple lasing areas 2 where current is confined toisolated regions in the structure where conductivity exists as comparedto the nonconductive ion-implanted areas. The conductive andnonconductive areas form a grid of light which has a single metalcontact on the single solid structure for the active positive (P)contact and a single negative (N) contact on the surrounding groundstructure which is shorted to the N contact area at the bottom of thetrench isolating the two areas or to negative metal on the surroundingground structure which is shorted to the N contact area at the bottom ofthe trench isolating the two areas (as in, for example, FIG. 7E (seereference numbers 781 and 782). These P and N contacts are then bondedto a high speed electrical contact, thereby enabling the lasing grid toachieve high frequency operation.

While FIG. 1 shows the lasing areas 2 arranged in a grid pattern, itshould be understood that many shapes and patterns of lasing areas 2could be formed. This allows many forms of structures withshapes/patterns of lasing areas 2 such as a honeycomb structure pattern(see, for example, FIG. 23 which illustrates another pattern which isone of many allowing different laser shapes or patterns; there are manypatterns that can be used for etching or implanting to leave conductiveareas 41 for lasers in a single mesa structure versus non-conductiveareas 42) and other structure patterns which are more rigid whileimproving bonding. Heat removal can still be accomplished by depositingmaterials with high thermal conductivity materials in the holes that areetched into the single mesa structure to produce the multiple lasers(see, e.g., holes 7005 in FIG. 7A) which are closer to the junctions.Examples of additional structure patterns can include arrangements likesquares or circles on lines, etc.

FIG. 1 shows a top view of the epitaxial side of a laser chip. A singlelaser-emitting epitaxial structure 1 has an ion-implanted area, allexcept the lasing areas 2 (which are shown as disks in FIG. 1 ) wherethe ion implant was masked. FIG. 1 thus represents the chip afterimplant, and etch. Relative to the prior design of US Pat App Pub2011/0176567 which has multiple epitaxial mesas with each mesacorresponding to a single lasing region, the design of FIG. 1 shows asingle contiguous structure 1 that does not have multiple mesas and caninstead be characterized as a single mesa, where this single mesaincludes multiple lasing regions 2. The illustration of FIG. 1 is meantto show the single mesa structure and not the electrical contacts. Thisstructure 1 could be either bottom emitting or top emitting depending onthe design and reflectance on the N mirror as compared to the P mirror.

FIG. 1 shows:

-   -   1 Single Active Mesa Structure which will produce multiple        lasing points    -   2 Areas where implant is masked so that implant does not affect        epitaxial region under mask.    -   3 Etched isolation trench separating the Single Active Mesa        Structure and the Single Ground Structure    -   4 Single Ground Structure

FIG. 2 is a cutaway view of the laser chip shown by FIG. 1 , where thesingle active mesa structure 1 shown by FIG. 1 is numbered as 11 in FIG.2 and where the masked implant areas 2 shown by FIG. 1 are numbered as12 in FIG. 2 . FIG. 2 represents the chip after implant, and etch but notop metal. Etched region 13 isolates the single mesa structure 12 fromthe “frame” or N mesa 14 (where the single ground structure 4 from FIG.1 is shown as the frame/N mesa 14 in FIG. 2 ). FIG. 2 shows:

-   -   11 Implanted area of Single Active Mesa Structure isolating        multiple lasing points    -   12 Areas of the Epitaxy Masked from Implant which will produce        lasing    -   13 Etched isolation trench separating the Single Active Mesa        Structure 11 and the Single Ground Structure 14    -   14 Single Ground Structure    -   15 Quantum wells between the top P mirror and the bottom N        mirror—this is an active region where Photons are emitted    -   16 N mirror which has N contact layer or highly doped layers for        N metal electrical contact location    -   17 Laser substrate

FIG. 3 is a perspective view of the chip shown by FIGS. 1 and 2 . Theimplanted region is invisible. The metal contacts are not shown. Thisillustration is to show the topology of the single mesa etch, which canbe used for either top-emitting or bottom-emitting implanted devices.The process of implant can take place before or after top metal or etch.

FIG. 4 shows a top view of the epitaxial side of an example top emittingVCSEL grid structure. The view is through a square hole in the topelectrical waveguide which is bonded by a solder process to the laserchip. The isolation etched region is hidden in this view by theelectrical waveguide. The round disks on this illustration are the holesin the top metal contact or plated metal contact region over the singlesolid mesa structure. FIG. 4 shows:

-   -   41 Hole in substrate with waveguide underneath    -   42 Holes in the top P metal so laser beams can emit through    -   43 Top of waveguide substrate    -   44 Top spreading metal on laser chip

FIG. 5 illustrates a cutaway view of the bonded electrical waveguide andlaser chip shown by FIG. 4 . The signal contact for the electricalwaveguide is opened to allow the beams to propagate through the opening.Another option of this embodiment would be to have a transparent ortransmitting substrate material for the waveguide instead of a hole forthe lasers to propagate through. A transparent material such as CVD(Chemical Vapor Deposited) diamond or sapphire or glass could be anexample of that material. This figure shows the embodiment with asubstrate such as AlNi which is opaque and thus needs a hole or opening.Notice the isolation region is separating the single mesa structure fromthe single mesa ground or structure or “frame” structure which isshorted to ground.

These P and N contacts are bonded to a high speed electrical contact(see also FIG. 7D, reference numbers 751 through 754). Theground-signal-ground (GSG) electrical waveguide substrate and laserchips are aligned (see FIG. 14B) so that the negative mesa is bonded tothe negative part of the waveguide and the positive active areas whichlase are aligned to the signal pad. This alignment is defined by abonder, then heat and pressure are applied to bond the solder that hasbeen deposited on one chip or the other (see FIG. 15 ) The high speednature of this contact arises because the p pad is separated from the nwafer ground by plating and solder heights but mostly by removing it offthe laser substrate and placing it on an electrical waveguide substrate.The physical separations dramatically reduce capacitance, therebyincreasing the frequency response (where the frequency response islimited by the capacitance of the circuit) and yielding high frequencyoperation for the lasing grid.

In an example embodiment, for high speed operation, the surface connectsto the electrical contact at the bottom of epi design, which isaccomplished through the isolation trench (see, for example, FIG. 7Breference number 702) surrounding the single structure (see, forexample, FIG. 7B (reference number 717)). This structure is not based onmesa topology but is simply shorted to the electrical region of the Ncontact metal (see FIG. 7B (reference number 703)) through the metalplating (such as in FIG. 7E reference number 782). This is not a builtup structure or raised structure as described in US Pat App. Pub.2011/0176567 but rather uses the chip surface and the epi material to bea surface for bonding, which also makes the device much more stable androbust at bonding.

Returning to FIG. 5 , the GSG Signal Pad 51 has Solder 52 electricalconnecting the P Contact Metal on the top of the Active Single MesaStructure. This allows the signal or current to be injected into themetal contact structure with holes in it for laser propagation and thenthe current flows through the non-implanted regions of the epitaxialstructures forcing current to be confined to just those defined regions.The top P mirror region has a slightly lower reflectance than the bottomN mirror allowing the light to emit from the top of the epitaxialstructure. The current flows on through the quantum wells which producethe light and heat in there junction, and into the n mirror where itproceeds to the N contact region in or near the n mirror. The currentwould then proceed up the shorted frame structure which is bonded and inelectrical contact to the ground portion of the GSG electricalwaveguide. This structure which utilizes top emitting design can be usedfor lower wavelength output designs which are lower than thetransmission cutoff of the GaAs or laser substrate material. Backemitting structures can typically only be designed for wavelengths above˜905 nm. This top emitting structure could be used with ˜850 nm or lowerto the limits of the epitaxial material set.

A single solid structure isolated from a surrounding ground with an etchwhere the single solid structure has within it ion implants; theimplants are invisible but cause the semiconductor material to benonconductive because of the crystal damage it causes. In order to makean implanted device you must mask the areas that are to be protectedfrom the damage first.

Small mesas are formed with photoresist positioned by aphotolithographic process which protects the epitaxial material fromdamage then is washed off after the implant takes place. The implanthappens in an ion implant machine which accelerates ions down a tube andyou put the wafer in front of the stream of ions.

Implanted ions can create areas of the semiconductor material that arenon-conductive. These areas of non-conductive material will force thecurrent flow through the lase areas. These non-conductive areas can alsobe created by etching a pattern similar to FIG. 1 and oxidizing thesingle structure as described below in connection with Embodiment 2.FIG. 5 shows:

-   -   50 Non Conducting Electrical Waveguide Substrate    -   51 Signal metal of electrical waveguide    -   52 Solder metal for bonding electrical waveguide to laser chip    -   53 Plated Metal shorted to Contact Layer and electrically        connected to Signal pad of GSG electrical waveguide    -   54 P Output Mirror—Diffractive Bragg Reflector    -   55 Active Region—Quantum Wells    -   56 N Mirror where low resistance contact Layer is located    -   57 Plated Metal shorting or in electrical contact with N Contact        layer and to Ground Mesas    -   58 Solder in Electrical contact with Ground pad of electrical        high speed waveguide and in electrical contact with Grounded        Mesa structure    -   59 Area on Plated metal connected to P Metal on single mesa        structure for contacting signal pad on high speed electrical        waveguide

FIG. 24 shows a comparative view of different current flows as betweenan embodiment such as Embodiment 1 and the design taught by US Pat App.Pub. 2011/0176567. With US Pat App. Pub. 2011/0176567, each mesa issurrounded by an N metal contact area. This takes precious space or realestate on the chip as the processing to define those footstep metal ncontacts around each mesa require photolithography which limits howclosely you can space the mesas together. These limits lead to a lowerpower output per unit area than the new method. Therefore the goal ofthis old apparatus was an array for highest power and speed yet did nottake into account the vast improvement in power/area which would also bean improvement in the ultimate goal of highest Power with the highestSpeed. Also, this old method's N contact had to be large because of thestructural limitations from the old method has been removed with the newsingle structure.

With the new design described herein, a single structure has severallasers on it and only one contact around that single structure. The newstructure reduces that N metal area to the outside of the structuremaking the area per light element much smaller. This involves a large Ncontact layer calculated to carry the current load of the singlestructure. The higher current flow from the single contact can berealized through thicker metal and or thicker N contact region.

Embodiment 2—Bottom-Emitting Implant

FIG. 6 illustrates a cutaway view of an example of a second embodiment,where the second embodiment is a bottom-emitting device with implantedregions for current confinement. The GSG electrical waveguide can beseen solder bonded to the frame-ground structure and the active singlelaser mesa structure. FIG. 6 shows:

-   -   601 Electrical Waveguide Substrate    -   602 Ground Contact and Signal Contact in that order of GSG        Electrical Waveguide    -   603 Solder-Bonding GSG Waveguide to Laser Chip    -   604 Plating Metal electrically connecting Signal pad of        Electrical Waveguide to Lasers P contact    -   605 P contact Metal    -   606 Implanted Region that has been rendered non conductive    -   607 P mirror    -   608 Active region (quantum wells)    -   609 N Mirror    -   610 Conducting Layers in N Mirror where Implant has not reached    -   611 Laser Beams Propagating through Laser Substrate    -   612 Plating Metal shorted to N contact region    -   613 Frame Area Shorted to N Contact region    -   614 Solder electrically contacting N contact on Laser to Ground        on Electrical Waveguide    -   615 Etched region isolating large single mesa from Ground Frame

Process for Embodiments 1 and 2

An example embodiment of the process steps to create the singlestructure for embodiments 1 and 2 with implant current confinement canbe as follows.

-   -   Step 1. Use photolithography to mask areas which will not have P        Metal deposited.    -   Step 2. Deposit P Metal (typically TiPtAu ˜2000 A)    -   Step 3. Photolithography lift off and wafer cleaning. O2 descum        or ash all organics off wafer.    -   Step 4. Dielectric deposit (typically SiNx ˜<1000 A) used as an        etch mask    -   Step 5. Photolithographic masking using either photoresist or        metal deposited in areas to protect the epi material from being        damaged from the implant which makes the unprotected regions        non-conductive through ion bombardment. This step can be        performed later in the process but may be more difficult due to        more varied topology.    -   Step 6. Implant—Those skilled in the art of calculating the        implant doses will determine the dose and species of implant        needed to disrupt the materials structures to the depth which        will isolate the p regions and the quantum wells from each        other—    -   Step 7 Cleaning this photolithography is difficult due to the        implant and a deposition of metal over the photolithography such        as plating could help to make it easier to clean off the resist.    -   Step 8. Use photolithography to mask areas of dielectric which        will not be etched. This is the unique part which is the design        of the mask which creates a large isolated structure down        implants within that structure define where current cannot flow.    -   Step 9. Use plasma etch to etch through dielectric (typically Fl        based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 10. Etch pattern into Laser or Light Emitting Diode        Epitaxial material. Stop on Substrate or doped electrical        contact layer. This isolates a single large structure from the N        shorted regions around the chip    -   Step 11. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 12. Use photolithography to mask areas which will not have        N Metal deposited.    -   Step 13. Deposit N Metal (Typically GeAu/Ni/Au eutectic        composition of 80% Au/20% Ge by atomic weight. Total thickness        of AuGe layer ˜3000 A or more with ˜200 A Ni or more of other        diffusion barrier metal and ˜5000 A of Au or more This is also        unique hear where the n metal is deposited in the n contact        etched region and also up and over the N contact structure        shorting the structure to the n-contact.    -   Step 14. Clean off mask (typically called lift off). O2 descum        or ash all organics off wafer.    -   Step 15. Dielectric deposit (typically SiNx ˜2000 A) used as a        non-conductive isolation barrier    -   Step 16. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 17. Use plasma etch to etch through dielectric (typically        Fl based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 18. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 19. Use photolithography to mask areas which will not have        Plated Metal deposited.    -   Step 20. Plate areas with ˜4-5 um of Metal (typically Au) or Cu        if diffusion barrier can be deposited first.    -   Step 21. Use photolithography to mask areas which will not have        Solder deposited.    -   Step 22. Deposit Solder Metal (Typically AuSn/Au eutectic        composition of 80% Au/20% Sn by atomic weight. Total thickness        of AuSn layer ˜40000 A (4 microns) or more with ˜500 A Au on top        to stop any oxidation of Sn. This layer can be patterned and        deposited on the submount with electrical waveguide which is        bonded to the laser grid.

Embodiment 3—Top-Emitting Oxidation

In a third embodiment, oxidation rather than ion implantation is used tocreate the grid of top-emitting lasing regions within the singlestructure. For example, a patterned etch can isolate conductive paths ina single structure, creating a grid of light sources. This structureexhibits multiple laser emission points from the single structure. Thelasing structure is isolated with an etched region from the groundcontact that forms the outside perimeter of the chip. This structure forEmbodiment 3 is top emitting. The conductive areas of the grid are wherelight will be emitted. The positive electrical contact can be a gridwith openings where the light is emitted.

The epitaxial material of the laser wafer can be a VCSEL design, andmost VCSELs are top emitting. The distribution of the signal using a ptype waveguide pad is typically on the laser wafer, but it should beunderstood that in an oxidated single structure embodiment that has aback emitting design, the waveguide can be on a separate substrate thatis separated from the laser n material or layer.

FIG. 7A, which shows an example of Embodiment 3, illustrates an examplepattern etched into a wafer to create a single structure which allowsmultiple point lasing. The single structure of an embodiment such asthat shown by FIG. 7A is much more rigid than the thin columns made offragile crystal material as taught by US Pat App. Pub. 2011/0176567.Also, as explained with respect to an embodiment discussed above, itshould be understood that pattern of lasing areas other than that shownby FIG. 7A may be employed if desired by a practitioner.

In FIG. 7A, the diagonally striped areas are preferably etched down tocreate the patterned single mesa structure in the middle of theisolation trench. All diagonally striped areas are preferably etcheddown to the bottom N electrically conductive layer 705 in FIG. 7B ortypically the larger isolation trench will be etched to the electricalcontact buried in the epitaxial design, while the smaller patterned etchareas must go deeper than the active region which isolates the lasingpoints. The patterned structure in the middle of the isolation trench isa single structure with “shaped” holes etched into it.

The holes in the large single mesa are large in this case. These holesallow the oxidation process environment to oxidize the layers in theepitaxial region. The oxide layer or layers has high aluminum contentand forms AlO₂ that grows laterally through the layer until taken out ofthe oxidation process. White areas are the surface of the chip, dottedlines are where oxidation limits current flow to unoxidized areas only.The holes in the large single mesa are large in this case. These holesallow the oxidation process environment to oxidize the layers in theepitaxial region. The oxidation layer can be formed by using a high Alcontent layer in the epi design structure which is buried below thesurface. The etched areas expose that layer which is then placed in anoxidation chamber allowing the exposed layer to oxidize inward, whereAlO₂ grows laterally through the layer until taken out of the oxidationprocess. As the length of the oxidation grows in that thin layer, itisolates or closes off the current paths with a dielectric material ofAlO₂ that is formed during the oxidation process. If the areas 7005 areetched, then the oxidation will continue to grow until only areas 7008are conductive and the area or part of the epitaxial layers whichconduct the current through that section. Electrically conductive areasallow current flow through the quantum wells (see FIG. 7B referencenumber 707) and produce lasing as the light is trapped in the cavitybetween the p mirror 709 and N mirror 706.

The oxidation length can be seen in FIG. 7A as dotted lines, all aboutthe same distance from any one exposed edge or holes in the large singlestructure that has holes formed in it. FIG. 7A also shows the largesingle mesa ground structure. Three views of cross sections areillustrated to identify where FIGS. 7B, 7D, and 7E are located. NoteFIG. 7D which clearly shows through this cross section that the mesa inthe center is a single structure.

FIG. 7A shows:

-   -   7001 Frame (Single Shorted Mesa) for Electrical Contact to        Ground of Electrical Waveguide    -   7002 Etched region isolating large single mesa from Ground Frame    -   7003 Single Mesa Structure with Etched Holes    -   7004 Indents in Edges to keep edges of Single Mesa Structure        Oxidized and Non Conductive    -   7005 Etched Hole in Single Mesa Structure    -   7006 Oxidation Pattern around any Etched Edges    -   7007 Overlapped Oxidized Areas not allowing Current Flow    -   7008 Laser Aperture where Current Flows freely (same as 761 in        FIG. 7D)    -   7009 Gap in Shorted Mesa Structure to Reduce Capacitance from        Ground to Signal Pad on Electrical Waveguide

FIGS. 7B, 7C and 7D are side views of the example FIG. 7A embodiment.

FIG. 7C shows the etched holes 727 that allow the oxidation 731 to form,which confines the current into region 761 of FIG. 7D, for formation oflaser beams 763.

Reference number 706 in FIG. 7B is a p mirror diffractive Braggreflector (DBR) which has one or more layers in it with very highaluminum content 708 which when exposed to hot damp conditions oxidizes708 confining the current to the areas 761 shown by FIG. 7D, which arewhere the laser beams come out. The N mirror DBR 709 has a conductivelayer 705 to take the current flow out through the N metal ohmic contact703 to the plating 782 (see FIG. 7E) which goes up and over the singleground mesa structure 718 (see FIG. 7B) to the solder 717 andelectrically connecting to the N plating on the GSG waveguide 716 andinto the N contact 715 of the waveguide.

Current confinement is a major part of a semiconductor laser. Theconcept is to force the current flow away from the edges of thestructure so there is not an issue with current flowing near roughsurface states that may exist from the etch. The current flow is alsoideally concentrated to create lasing by increasing the current densityin the material The current confinement occurs either by oxidationthrough allowing the high concentrate layers of Al to get exposed by hotdamp conditions in the oxidation process enabled by the drilled holes(e.g., this Embodiment 3), or by the implant to render all other areasnonconductive (e.g., see Embodiments 1 and 2).

FIG. 7B shows:

-   -   701 Electrical Waveguide Substrate    -   702 Etched region isolating large single mesa from Ground Frame    -   703 N Metal contact electrically contacting N contact layer    -   704 N Mirror    -   705 N Contact layer in N mirror (low resistance for ohmic        contact)    -   706 N Mirror above N contact region    -   707 Active region (quantum wells)    -   708 Oxidized Layer Closing off Current in these Regions    -   709 P mirror    -   710 Dielectric Layer    -   711 Plating on top of P contact Metal    -   712 Aperture in P Contact Metal and Plating Metal for laser beam        exit    -   713 Electrical Waveguide Substrate    -   714 Ground Contact of GSG Electrical Waveguide    -   715 Signal Contact of GSG Electrical Waveguide    -   716 Solder-Bonding GSG Waveguide to Laser Chip    -   717 Solder-Bonding GSG Waveguide to Laser Chip    -   718 Frame structure electrically connected to N contact region        of laser chip

FIG. 7C is a continuation of FIG. 7B above, and it further shows:

-   -   721 Ground Contact of GSG Electrical Waveguide    -   722 Plating on Ground Contact of GSG Electrical Waveguide    -   723 Solder-Bonding GSG Waveguide to Laser Chip    -   724 Signal Contact of GSG Electrical Waveguide    -   725 Solder-Bonding GSG Waveguide to Laser Chip    -   726 Plating on Signal Contact of GSG Electrical Waveguide    -   727 Etched Hole Regions in Single Mesa Substrate permits        oxidation to form Current Confinement Apertures    -   728 Plating on top of P contact Metal    -   729 Opening in Dielectric layer for electrical contact from        Plating to P Contact Layer on Laser Single Mesa Structure    -   730 Dielectric Layer    -   731 Oxidation Layer closing off current near Etched Hole Regions

FIG. 7D is a FIG. 7A cutaway view that also shows the electricalconnections and electrical waveguide that are not shown in FIG. 7A. FIG.7D illustrates the cross section through the apertures created by theoxidized layer. The oxidized layer is exposed to the oxidation processthrough the holes in the single structure illustrated in FIG. 7B. Thisview also shows that the Active Mesa Structure is truly a Single MesaStructure. FIG. 7D depicts:

-   -   751 Ground Contact of GSG Electrical Waveguide    -   752 Plating on Ground Contact of GSG Electrical Waveguide    -   753 Solder-Bonding Ground of GSG Waveguide to Laser Chip    -   754 Signal Contact of GSG Electrical Waveguide    -   755 Plating on Signal Contact of GSG Electrical Waveguide    -   756 P contact Metal on Laser Chip    -   757 Opening in plating and P Contact Metal over Laser Aperture    -   758 Plating on P Contact Metal    -   759 Solder-Bonding Signal of GSG Waveguide to Laser Chip    -   760 Dielectric Layer Protecting Active Mesa Structure from N        Contact    -   761 Current Confinement Aperture formed by opening in Oxidation        Layer    -   762 Oxidation Layer Dielectric    -   763 Laser Beam Propagating through Metal Opening

FIG. 7E is a cross sectional view of the area where the P Contact orSignal of the GSG waveguide is positioned below the Laser Chip where theN Contact Frame or single structure mesa grounded to the N contact ofthe laser is above the GSG Electrical Waveguide. The large gap betweenthe Laser Ground and the P Signal Pad reduces the capacitance of thecircuit enabling higher frequency operation. FIG. 7E depicts:

-   -   780 Dielectric Layer    -   781 N Type Ohmic Contact Metal    -   782 Plating Shorting N Metal Contact to Single Ground Mesa        Structure    -   784 N Contact Layer in Epitaxial Growth    -   785 Plating Electrically Contacted to Signal Pad on Electrical        Waveguide    -   786 Metal Signal Pad Lead on GSG Electrical Waveguide    -   787 Plating on Ground Pad of GSG Electrical Waveguide    -   788 Electrical Waveguide Substrate    -   789 Gap between Conductive Signal Pad Structure and N Contact        Layer Reduces Capacitance

Process for Embodiment 3

An example embodiment of the process steps to create the singlestructure for embodiment 3 with oxidation current confinement can be asfollows.

-   -   Step 1. Use photolithography to mask areas which will not have P        Metal deposited.    -   Step 2. Deposit P Metal (typically TiPtAu ˜2000 A)    -   Step 3. Photolithography lifts off and wafer cleaning. O2 descum        or ash all organics off wafer.    -   Step 4. Dielectric deposit (typically SiNx ˜<1000 A) used as an        etch mask    -   Step 5. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 6. Use plasma etch to etch through dielectric (typically Fl        based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 7. Etch pattern into Laser or Light Emitting Diode        Epitaxial material. Stop on Substrate or doped electrical        contact layer. Typically the etch is Cl based with some (high        percentage) amount of BCl3.    -   Step 8. Clean off mask. O2 descum or ash all organics off wafer.    -   Step 9. Use photolithography to mask areas which will not have N        Metal deposited.    -   Step 10. Deposit N Metal (Typically GeAu/Ni/Au eutectic        composition of 80% Au/20% Ge by atomic weight. Total thickness        of AuGe layer ˜3000 A or more with ˜200 A Ni or more of other        diffusion barrier metal and ˜5000 A of Au or more    -   Step 11. Clean off mask (typically called lift off). O2 descum        or ash all organics off wafer.    -   Step 12. Dielectric deposit (typically SiNx ˜2000 A) used as a        non-conductive isolation barrier    -   Step 13. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 14. Use plasma etch to etch through dielectric (typically        Fl based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 15. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 16. Use photolithography to mask areas which will not have        Plated Metal deposited.    -   Step 17. Plate areas with ˜4-5 um of Metal (typically Au) or Cu        if diffusion barrier can be deposited first.    -   Step 18. Use photolithography to mask areas which will not have        Solder deposited.    -   Step 19. Deposit Solder Metal (Typically AuSn/Au eutectic        composition of 80% Au/20% Sn by atomic weight. Total thickness        of AuSn layer ˜40,000 A (4 microns) or more with ˜500 A Au on        top to stop any oxidation of Sn. This layer can be patterned and        deposited on the submount with electrical waveguide which is        bonded to the laser grid.    -   Step 20. Separate laser chips from wafer with cleaving or        dicing.    -   Step 21. Design and Fabricate electrical waveguide to align to        laser chip with the design to allow high frequency operation.    -   Step 22. Align and Flip Chip Bond the laser chip to the Submount        electrical waveguide

Embodiment 4—Bottom-Emitting Oxidation

In a fourth embodiment, an oxidated single structure with multiplelasing regions is designed as a bottom-emitter rather than a topemitter. FIG. 8 through FIG. 14C provide details about Embodiment 4 andillustrate the process which can be used to make this embodiment. Thelasing grid's light is emitted through the substrate forming a backemitter.

Light is transmissive in GaAs from wavelengths around 900 nm andgreater. If the wavelength of the light engineered in the epitaxialdesign is in the range ˜900 nm and above, the GaAs substrate transmitsthe light or is transparent to the light. If the epitaxial designincludes an N mirror that is less reflective than the P mirror, a lasersuch as a VCSEL can emit the light from the N mirror through thesubstrate. The laser beams will propagate through the material, and thesubstrate can be a platform for optical components to collimate, spread,diverge, converge or direct the light. This enables integrated opticalcircuits with extremely high bright power to be formed. The singlestructure and the ground contact can then be integrated to a high speedelectrical waveguide substrate enabling high frequency responses fromthe entire grid. A ground signal ground electrical waveguide is idealfor this high speed electrical waveguide. Another type of electricalwaveguide that may be used is a microstrip waveguide (see FIG. 15 ),where the signal pad is separated from the ground pad by a thindielectric layer on a substrate.

FIG. 8 is an illustration of a typical epitaxial design. Any high speeddesign can be used for VCSEL devices. FIG. 8 shows:

-   -   81 GaAs substrate    -   82 Possible position for low resistance contact layer    -   83 N Mirror layer after contact region    -   84 Low resistance N contact region    -   85 N Mirror layer after quantum wells    -   86 Quantum Well Region    -   87 Oxidation layers    -   88 P Mirror    -   89 Low resistance P Contact layer

FIG. 9 is an illustration of the first process performed, which is Pmetal deposit. This is typically a Ti/Pt/Au Layer on top of the highly Pdoped Contact Layer forming an ohmic contact. FIG. 9 shows:

-   -   91 P Metal forming Ohmic Contact after annealing process    -   92 Low Resistance P Contact Layer

FIG. 10A is a top view of the etch of the epitaxial layer down to the Ncontact layer. FIG. 10A shows:

-   -   1001 Etched Area to N Contact Layer    -   1002 Single Mesa Ground Structure    -   1003 Single Mesa Active Structure    -   1004 Etch Hole to Allow Oxidation Process to form Apertures    -   1005 Area in between all holes where there will be no oxidation        which forms conductive current confinement

FIG. 10B is a cross section view A of FIG. 10A formed before oxidationprocess, and FIG. 10C is a cross section view A of FIG. 10A formed afteroxidation process. FIG. 10C shows:

-   -   120 Oxidation completely closes off conductive path near any        etched regions that were exposed during the oxidation process.

FIG. 10D is a cross sectional view B of FIG. 10A illustrating where thecurrent confinement apertures were formed in the areas shown. This viewrepresents a section of the single mesa where no holes are penetratingthe cross section, and clearly shows that the mesa structure is a SingleMesa Structure enabling a more robust structure preferred at the bondingprocess. FIG. 10D shows:

-   -   125 Current Confinement Aperture is conductive region of Single        Mesa Structure    -   126 Oxidized Layer forming as dielectric layer near where holes        where etched    -   127 P Metal Contact Layer

FIG. 11 illustrates the dielectric layer deposited and patterned withopened via “holes” for electrical contact to the epitaxial contactlayers and sealing the semiconductor for reliability purposes. FIG. 11shows:

-   -   1101 Dielectric Layer patterned with openings or “vias”    -   1102 Opening in Dielectric Layer to P Contact Metal    -   1103 Contact Layer on Single Mesa Ground Structure

FIG. 12 shows the N metal contact after it has been deposited. FIG. 12depicts:

-   -   1201 N Contact Metal is deposited over the N Contact via hole to        make an electrical connection to the N Contact Layer.

FIG. 13 illustrates the next step of plating metal which shorts the Ncontact region to the top of the single grounded frame region, whichwill be bonded and electrically conductive to the ground pad of the GSGwaveguide. The plating also adds height to the active region reducingcapacitance and it removes heat from the active region of the devices togive the devices better performance. The plating over the active singlestructure is isolated from the N mirror and N contact region by thedielectric layer. FIG. 13 shows:

-   -   1301 Dielectric Layer preventing the Plating covering the Active        Region and extending into the holes of the single mesa structure    -   1302 Plating Covering Single Grounded Mesa Structure Shorted to        N Contact Region through N Contact Metal    -   1303 Plating Covering Active Structure and extending into the        holes of the active region where cooling can occur through a        higher thermal conductance of the plating metal    -   1304 Plated Metal extending over single frame structure for        bonding and electrically connecting to ground of GSG electrical        waveguide.

FIG. 14A illustrates solder deposited on the laser chip. This serves asthe electrical conductive bonding adhesion layer between the laser chipand the high speed electrical waveguide. FIG. 14A shows:

-   -   1401 Solder deposit

FIG. 14B illustrates the alignment of the GSG electrical waveguidebefore bonding. FIG. 14B shows:

-   -   1403 Submount for GSG Electrical High Speed Waveguide    -   1404 Ground Pad for GSG Electrical High Speed Waveguide    -   1405 Signal Pad for GSG Electrical High Speed Waveguide    -   1406 Plating Metal Deposited on Conductive areas of GSG        Electrical High Speed Waveguide

FIG. 14C illustrates the bonded laser chip to the GSG electricalwaveguide. The gap in the single grounded mesa enables high speedoperation by reducing capacitance.

Embodiment 5

In a fifth embodiment, a microstrip or strip line electrical waveguideis used rather than the GSG waveguide, as shown by FIG. 15 . Thisembodiment can also have the gap mentioned in FIG. 14C above. Thiselectrical waveguide can also be formed by a ground layer below a thindielectric with a signal lead on the top of the dielectric forming astrip line or microstrip waveguide. Openings in the dielectric can beused to contact the ground portion of the lasing grid. The width of thelines and thickness of the dielectric can be controlled to produce aspecific impedance value for circuit matching characteristics. It shouldbe understood that this technique can also be used for otherembodiments, such as Embodiment 2 or any of the embodiments discussedbelow. The view in FIG. 15 shows a cross section across the activesingle mesa structure:

-   -   151 Waveguide substrate    -   152 Metal Ground Pad across the entire waveguide    -   153 Dielectric layer separating the Ground from the signal pads    -   154 Metal Signal Pad    -   155 Metal Plating on Signal pad    -   156 Solder electrically connecting the signal pad to the single        active mesa shown here with gaps or holes etched into it.    -   157 Metal Plating on the Ground Pad    -   158 Solder electrically connecting the ground pad to the single        grounded mesa

Embodiment 6

FIG. 16 shows a sixth embodiment. In FIG. 16 the structure is unique inthat it leaves paths for a portion of the light of each lase point to bedirected to another laser next to it in order to keep the lasing inphase. In this example the laser 161 has some of its outer modestructure reflected 162 down to the laser aperture next to it 163 whichproduces light in phase with 162. The laser which is in phase is 164 andin turn reflects from an angled reflective surface 165 back to theaperture of the laser next to it 167 which is also in phase with 164 and161 and so on. An angular and or reflective area 164 just outside of thelens or output area can divert a small portion of the light which isoverflowing from the lens or output diameter to the lasing grid adjacentto it, enabling a coherent lasing grid. Some of the light from theneighboring lasing points is injected into the lasing point which setsup the lasing points in a phase relation with each other. This allows acoherent operation of all lasing points when the structure directs someof the light from each laser to its neighbor. The reflectance, distanceand angles are very precisely calculated by one skilled in the art ofoptical modeling. Coherent operation is a benefit which has eluded laserarray operation for many years. FIG. 16 shows:

-   -   161 Large aperture laser with wide divergence only emitting a        portion of the light    -   162 A portion of the light from laser 161 is reflected to        aperture 163    -   163 Aperture of laser where reflectance conforms to the phase of        the light from 162    -   164 Large aperture laser with wide divergence only emitting a        portion of the light    -   165 Angled reflective surface on the back of the laser chip just        outside the output aperture    -   166 the reflected beam in phase with laser grid 164    -   167 Large aperture laser with wide divergence only emitting a        portion of the light

Embodiment 7

FIG. 17 shows a seventh embodiment. In FIG. 17 , the back side of thelasing grid chip has etched patterns to redirect the laser light 172 toparticularly beneficial areas. This is accomplished by diffractiveoptical elements (DOE) 171, which have the surface etched in a way thatwhen light travels through that portion, the angle of the surface andredirects 175 beams or light depending on the angle of the surface ofthe DOE. This can be used to collimate or diverge, direct or homogenizethe light. FIG. 17 does not illustrate the electrical waveguide. Themode can be controlled by the aperture sizes and characteristics of thereflective surface 173 and 174. FIG. 17 shows:

-   -   171 Redirected Laser Grid Beam from beam 172    -   172 Laser Grid Beam emitted from apertures    -   173 Contact and back of mirror for back emitting laser grid    -   174 Contact and back of mirror for back emitting laser grid    -   175 Redirected beams from laser grid

Embodiment 8

FIG. 18 shows an eighth embodiment. In FIG. 18 , a patterned diffractivegrating 184 (this is the opposite angular pattern than FIG. 17 's DOE)is placed or etched over the emission points 181 on the backside of thelaser wafer in a back emitting VCSEL design which directs the lasingpoints outward 185 from the grid. From the lens it looks like all thelasers are coming from a single point 186 behind the chip to form avirtual point source where a macro lens 187 can be used to collimate thebeam from the virtual converged source behind the chip. FIG. 18 shows:

-   -   181 Contact and back of mirror for back emitting laser grid    -   182 Aperture creating laser characteristics    -   183 Laser Beam from laser grid    -   184 Surface of Diffractive Optical Element (DOE) angled for        specific total beam grid characteristics    -   185 Redirected beams from laser grid    -   186 Converged virtual light source from all beams as seen from        lens 187    -   187 macro lens with focal point on virtual convergence point 186

Embodiment 9

FIG. 19 shows a ninth embodiment. FIG. 19 illustrates a cross section ofthe bonded etched and oxidized Embodiment 3, except it has microlenswhich have been processed on the back of the laser chip and positionedso that one is aligned to the other and one is slightly misaligned onpurpose in order to redirect the laser beam emitted from the single mesastructure. While embodiment 3 is referenced for this arrangement, itshould be understood that any of the above back emitting embodiments anda microlens array attached to the chip or positioned above the outputgrid can be used. The microlens array can have values related to thepitch of the light conducting grid points but with a slightly differentpitch lens 74 forcing the light emitted by the lasing points to bedirected to a single area where the beams come together or seem likethey come together in front of the chip or behind the chip as in avirtual point source. If the microlens pitch is smaller than the laserpitch, it will guide the outlying lasers to a point in front of the chipor directed inward. If the microlens arrays pitch is larger than thelasers' grids' pitch, the light will be directed outward as in FIG. 19 .FIG. 19 shows:

-   -   71 Laser Substrate    -   72 N Mirror    -   73 N Contact Region    -   74 MicroLens slightly offset from laser directing laser light        outward    -   75 Active region or quantum wells    -   76 Oxidized layers creating current confinement into the active        area    -   77 Etched trench creating isolation from the single ground        structure and the active single mesa structure    -   78 P Metal Contact    -   79 Hole Etched into the single mesa structure to allow oxidation        to occur    -   80 solder electrically connecting the laser chip and the High        speed electrical waveguide    -   81 Signal pad of the GSG electrical waveguide    -   82 P mirror    -   83 GSG Waveguide substrate    -   84 Plating shorting the N metal located on the N contact layer        and the single ground mesa which is in electrical contact to the        Ground Pad of the GSG electrical waveguide    -   85 Ground Pad of the GSG electrical waveguide

Embodiment 10

FIG. 20 shows a tenth embodiment. FIG. 20 illustrates that an extendedcavity laser design can be implemented using the single grid structureby reducing the reflectivity of the N epitaxial output mirror 230 to apoint where it will not lase, then adding the reflectivity to areflective surface 231 on the back of the lasing grid which extends thecavity. This structure reduces feedback of the higher mode structure 233in the cavity, thereby forming a more fundamental mode structure for theoutput beam 235 from the grid. FIG. 20 shows:

-   -   230 Arrow pointing to incomplete N output mirror epitaxial        region.    -   231 Reflective region made of dielectrically layers with varying        indexes of refraction.    -   232 Cavity of laser beam now includes laser wafer material        extending the cavity for modal rejection.    -   233 Reflected higher order modes which are not reflected back        into the cavity    -   234 Single or lower order modes in the cavity    -   235 single or lower order modes outputted from the Extended        Cavity Device

Embodiment 11

FIG. 21 shows an eleventh embodiment. In FIG. 21 , a VCSEL structure canbe adapted to the laser grid design like the above embodiment, and theback of the lasing chip where the output reflector (deposited on top oflens shape 241) of the lasing grid emits light can have convex 241 orconcave features under the reflector to form better a focused (focusarrows 243) feedback mechanism which rejects high modes and can bedesigned to have a single mode lasing output 245 from each grid area.The overall lasing structure will then have low M2 values. A lens ormicrolens can be added to collimate the output. FIG. 21 shows:

-   -   240 Arrow pointing to incomplete N output mirror epitaxial        region.    -   241 Reflective region made of dielectrically layers with varying        indexes of refraction deposited on top of microlens structure        etched into the laser substrate or wafer    -   242 Single mode beam being reflected within the extended cavity    -   243 light from edges being directed back into the single mode        cavity from the optical element on the surface of the chip    -   244 single mode beam has more power and is more selective of the        single mode than FIG. 20 's single mode beam    -   245 Output of high quality single mode beams    -   246 highly reflective epitaxial mirror

Embodiment 12

FIG. 22 shows a twelfth embodiment. In FIG. 22 , a VCSEL structure canbe adapted to the laser grid design like the above embodiment exceptthat the beams which exit straight out of the lens go through anexternal microlens array which has been designed with different pitchmicrolens than the laser pitches to allow redirection of the beamseither to or from a single location like many of the above embodiments.Other forms of this technique could use a concave lens formed on thebottom of the external lens array which are aligned and have the samepitch as the laser grid, while a convex laser array with a differentpitch than the laser grid is at the top. Another technique to directbeams would be to use DOEs as the top optical element instead of theconvex microlens which are on the top of the external lens array. 252 islight reflected back into the center of the aperture making a strongersingle mode beam while 253 has the reflective coatings which completethe laser output mirror cavity. 254 is the cavity and would have anantireflective coating deposited on the inside of the external lenscavity while also depositing an anti-reflective coating on the topmicrolens array. Another technique would be to use the flat reflectiveproperties such as in FIG. 20 to complete the cavity mirror and have themicrolens array offset on the top or a DOE on top to redirect the beams.FIG. 22 shows:

-   -   250 Arrow pointing to incomplete N output mirror epitaxial        region.    -   251 Single mode beam being reflected within the extended cavity    -   252 light from edges being directed back into the center        creating strong single mode cavity from the optical element on        the surface of the chip    -   253 Reflective region made of dielectrically layers with varying        indexes of refraction deposited on top of microlens structure        etched into the laser substrate or wafer    -   254 Cavity for etched lens to not touch external lens array    -   255 External lens array transmissive material    -   256 Single Mode beam outputted by extended cavity laser    -   257 Microlens from lens array with different pitch than laser        pitch directing beams    -   258 Directed single mode beam

While the present invention has been described above in relation toexample embodiments, various modifications may be made thereto thatstill fall within the invention's scope, as would be recognized by thoseof ordinary skill in the art. Such modifications to the invention willbe recognizable upon review of the teachings herein. As such, the fullscope of the present invention is to be defined solely by the appendedclaims and their legal equivalents.

What is claimed is:
 1. A multi-laser semiconductor apparatus comprising:an active mesa structure; a contact layer; a structure separated fromthe active mesa structure; a substrate that supports the active mesastructure, the contact layer, and the structure; and an electricalwaveguide; wherein the active mesa structure comprises a single mesahaving a plurality of semiconductor laser regions within the singlemesa, each semiconductor laser region of the single mesa beingelectrically isolated within the single mesa relative to the othersemiconductor laser regions of the single mesa; wherein the contactlayer extends beneath the active mesa structure; wherein the structureprovides a contact that shorts the structure to the contact layer toprovide a path for a current flow from the electrical waveguide todeliver energy to the semiconductor laser regions; wherein theelectrical waveguide provides the current flow to the semiconductorlaser regions and the structure via a plurality of electrical waveguidecontacts, the electrical waveguide contacts comprising a first contactfor electrical connection with the semiconductor laser regions and asecond contact for electrical connection with the structure contact; andwherein the contact layer is adapted to carry a current load from theelectrical waveguide and spread current laterally through the contactlayer to the active mesa structure including interior semiconductorlaser region portions of the single mesa for injecting the semiconductorlaser regions with current to produce lasing from the semiconductorlaser regions.
 2. The apparatus of claim 1 wherein the active mesastructure, the structure, the contact layer, and the substrate are partof a laser array, and wherein the first and second contacts of theelectrical waveguide connect to a single side of the laser array.
 3. Theapparatus of claim 2 wherein the laser array is a back emitting laserarray.
 4. The apparatus of claim 2 wherein the laser array is arrangedas an emitter for a light detection and ranging (LiDaR) system.
 5. Theapparatus of claim 4 wherein the laser array further provides opticalcommunication via the lasing produced from the semiconductor laserregions.
 6. The apparatus of claim 2 wherein the laser array furthercomprises a plurality of diffractive optical elements (DOEs), the DOEsadapted to collimate, diverge, direct, or homogenize light produced bythe semiconductor laser regions.
 7. The apparatus of claim 1 wherein thecontact layer has a thickness sufficient to carry the current load fromthe electrical waveguide and spread current laterally through thecontact layer to the active mesa structure including interiorsemiconductor laser region portions of the single mesa for injecting thesemiconductor laser regions with current to produce lasing from thesemiconductor laser regions.
 8. The apparatus of claim 1 wherein thecontact layer comprises an N contact layer, and wherein the apparatusfurther comprises: a P contact layer on top of the active mesastructure, and wherein the first contact of the electrical waveguide isin electrical connection with the P contact layer.
 9. The apparatus ofclaim 1 wherein the structure is arranged as a ground structure for theapparatus.
 10. The apparatus of claim 1 wherein the electrical waveguidecomprises a ground-signal-ground (GSG) electrical waveguide.
 11. Theapparatus of claim 1 wherein the electrical waveguide comprises amicrostrip or strip line electrical waveguide.
 12. The apparatus ofclaim 1 wherein the active mesa structure is arranged as a verticalcavity surface emitting laser (VCSEL) or a vertical extended cavitysurface emitting laser (VECSEL).
 13. The apparatus of claim 1 furthercomprising: a conductive frame around the active mesa structure thatshorts the electrical waveguide second contact to the contact layer. 14.The apparatus of claim 1 wherein a trench separates the active mesastructure from the structure.
 15. The apparatus of claim 1 wherein thestructure is around a periphery of the active mesa structure.
 16. Theapparatus of claim 1 wherein the semiconductor laser regions arearranged in a grid pattern, a honeycomb pattern, or a circle pattern onthe single mesa.
 17. The apparatus of claim 1 further comprising aplurality of active mesa structures, wherein each active mesa structurecomprises a single mesa, wherein each of the single mesas comprises aplurality of laser regions within that single mesa, each semiconductorlaser region of that single mesa being electrically isolated within thatsingle mesa relative to the other semiconductor laser regions of thatsingle mesa.
 18. The apparatus of claim 1 wherein the semiconductorlaser regions are electrically isolated from each other within thesingle mesa via oxidation layers or ion implantation.
 19. A multi-lasersemiconductor apparatus comprising: an active mesa structure; a contactlayer; a structure separated from the active mesa structure; a substratethat supports the active mesa structure, the contact layer, and thestructure; and an electrical waveguide; wherein the active mesastructure comprises a plurality of semiconductor laser regions withinthe active mesa structure itself, each semiconductor laser region of theactive mesa structure being electrically isolated within the active mesastructure itself relative to the other semiconductor laser regions ofthe active mesa structure; wherein the contact layer extends beneath theactive mesa structure; wherein the structure provides a contact thatshorts the structure to the contact layer to provide a path for acurrent flow from the electrical waveguide to deliver energy to thesemiconductor laser regions; wherein the electrical waveguide providesthe current flow to the semiconductor laser regions and the structurevia a plurality of electrical waveguide contacts, the electricalwaveguide contacts comprising a first contact for electrical connectionwith the semiconductor laser regions and a second contact for electricalconnection with the structure contact; wherein the contact layer isadapted to carry a current load from the electrical waveguide and spreadcurrent laterally through the contact layer to the active mesa structureincluding interior semiconductor laser region portions of the activemesa structure for injecting the semiconductor laser regions withcurrent to produce lasing from the semiconductor laser regions; andwherein the active mesa structure further comprises a plurality of holesextending therethrough, each hole having a layer of oxidation around it,the holes and the oxidation layers being positioned to define andelectrically isolate the semiconductor laser regions.
 20. A multi-lasersemiconductor apparatus comprising: an active mesa structure; a contactlayer; a structure separated from the active mesa structure; a substratethat supports the active mesa structure, the contact layer, and thestructure; and an electrical waveguide; wherein the active mesastructure comprises a plurality of semiconductor laser regions withinthe active mesa structure itself, each semiconductor laser region of theactive mesa structure being electrically isolated within the active mesastructure itself relative to the other semiconductor laser regions ofthe active mesa structure; wherein the contact layer extends beneath theactive mesa structure and is positioned above the substrate; wherein thestructure provides a contact that shorts the structure to the contactlayer to provide a path for a current flow from the electrical waveguideto deliver energy to the semiconductor laser regions; wherein theelectrical waveguide provides the current flow to the semiconductorlaser regions and the structure via a plurality of electrical waveguidecontacts, the electrical waveguide contacts comprising a first contactfor electrical connection with the semiconductor laser regions and asecond contact for electrical connection with the structure contact;wherein the contact layer is adapted to carry a current load from theelectrical waveguide and spread current laterally through the contactlayer to the active mesa structure including interior semiconductorlaser region portions of the active mesa structure for injecting thesemiconductor laser regions with current to produce lasing from thesemiconductor laser regions; and wherein the active mesa structurefurther comprises a plurality of conductive regions formed by ionimplantation, the ion implantation being positioned to define andelectrically isolate the semiconductor laser regions.